微乳液介质-5-Br-PADAP光度法测定原油中的锌

以水的质量分数为80%的O/W型十二烷基硫酸钠/正丁醇/正庚烷/水微乳液为介质,以2-(5-溴-吡碇偶氮)-5-二乙氨基苯酚(即5-Br-PADAP)为显色剂,氯化铵-氨水作为缓冲溶液,测定了原油中的锌。锌络合物的最大吸收峰位于555nm,锌在质量浓度为0～1mg/L范围内服从比尔定律,其表观摩尔吸收系数为1.24×105L·mol-1·cm-1。采用三乙醇胺和硫脲作为联合掩蔽剂消除其它离子的干扰,人工合成样品平均回收率在100.15%,相对标准偏差为1.13%。测定了扶余原油和大庆减渣中的锌,其相对标准偏差分别为2.11%和2.46%,加标平均回收率分别为101.96%、101.66%。以O/W微乳液为介质与相应的胶束体系相比较,锌的测定灵敏度提高2.5倍,该方法具有良好的准确性和选择性。

Microemulsion Medium- Spectrometric Determination of Zinc in Crude Oils With 5-Br-PADAP

The determination of zinc with 5-Br-PADAP was studied in the medium of O/W microemulsion SDS-n-C_4H_9OH-n-C_7H_(16)-H_2O and NH_3CL-NH_4·H_2O buffer solution (mass fraction of water is 80%). The complex compound of zinc maximum absorption wavelength is at 555 nm.The Beer's law is obeyed by zinc in the mass concentration range of 0 to 10 mg/L. The molar absorption coefficient is 1.24×10~5 L·mol~(-1)·cm~(-1). zinc in crude oil was determined while interfere ions were masked by triethanolamine and sulfourea solution as screening agent.The mean recovery rate of the synthetic sample is 100.15%. The RSD is 1.13%. The content of Zinc in Fuyu crude oil and Daqing vacuum residuum were determined. The relative standard deviation is 2.11% and 2.46% respectively. The mean recovery rate of standard added is 101.96% and 101.66% respectively. Comparing to the correspond micellar system, the sensitivity is enhanced 2.5 times in the medium of O/W microemulsion. The method has good accuracy and selectivity.